Cooperative Fish and Wildlife Research Units Program: Maine
Education, Research and Technical Assistance for Managing Our Natural Resources

Maine Project

Understanding downstream migratory survival of Atlantic salmon smolts in the Penobscot River Maine; effects of dams and restoration

January 2004 - September 2020


Participating Agencies

  • Brookfield Power
  • ARRA
  • NFWF
  • NOAA

The downstream migration of Atlantic salmon juveniles is a critical stage in their life cycle. During this stage, individuals undergo a series of morphological, physiological and behavioral changes that prepare them for the migration and for life at sea. Survival of juveniles in the Penobscot River has been studied since 2005, using acoustic and radio telemetry. Several areas of high concern, have been recognized - namely dams and the estuary. The system-wide survival of smolts in the Penobscot River has been consistently low throughout the years, but the influence of stocking timing, flow and delays are being revealed. Together with NOAA, USFWS, Penobscot Nation, we are working to understand how the range of conditions in the river can influence the odds of restoration success. These data are being used to inform both stocking strategies and stimulate innovative restoration techniques.

Research Publications Publication Date
Zydlewski J., Stich, D.S., and Sigourney, D. (2016) Hard choices in assessing survival past dams; a comparison of single and paired release strategies. Canadian Journal of Fisheries and Aquatic Sciences. (999) 1-13. DOI:10.1139/cjfas-2015-0480 | Download July 2016
Stich, D.S., Zydlewski, G.B., and Zydlewski J. (2015) Physiological preparedness and performance of Atlantic salmon Salmo salar smolts in relation to behavioural salinity preferences and thresholds. Journal of Fish Biology. doi:10.1111/jfb.12853 | Download December 2015
Stich, D.S., Zydlewski, G.B., Kocik, J. and Zydlewski, J. (2015) Linking behavior, physiology, and survival of Atlantic Salmon smolts during estuary migration. Marine and Coastal Fisheries. 7(1) 68-86. | Download April 2015
Stich, D.S., Kinnison, M., Kocik, J. and Zydlewski J. (2015) Initiation of migration and movement rates of Atlantic Salmon smolt migration in fresh water. Canadian Journal of Fisheries and Aquatic Sciences. 72(9): 1339-1351. | Download May 2015
Stich, D.S., Bailey, M.M. and Zydlewski J. (2014) Survival of Atlantic salmon Salmo salar smolts through a hydropower complex in the lower Penobscot River, Maine USA. Journal of Fish Biology. 85:1074-1096 | Download September 2014
Stich, D.S., Bailey, M., Holbrook, C., Kinnison, and Zydlewski J. (2015). Catchment-wide survival of wild- and hatchery-reared Atlantic Salmon smolts in a changing system. Canadian Journal of Fisheries and Aquatic Sciences. 2:1–14, | Download August 2015
Holbrook, C., M. Kinnison and J. Zydlewski. 2011 Survival of migrating Atlantic salmon smolts through the Penobscot River, Maine, USA: A pre-restoration assessment. Transactions of the American Fisheries Society 140(5): 1255-1268. | Download September 2011
Theses and Dissertations Publication Date
Stich, D.S. 2014. Phenology and effects of dams on the success of Atlantic salmon migrations in the Penobscot River, Maine. Ph.D. dissertation, Wildlife Ecology, University of Maine, Orono, 257 pp. December 2014
Holbrook, C. 2007. MS Thesis: Behavior and survival of Migrating Atlantic salmon (Salmo salar) in the Penobscot River and Estuary Maine: Acoustic Telemetry Studies of Smolts and Adults. March 2007